Symplectic manifolds and their lagrangian submanifolds
Symplectic manifolds and their lagrangian submanifolds
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DOI:
10.1016/0001-8708(71)90020-x
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发表时间:
1971-06
影响因子:
1.7
通讯作者:
A. Weinstein
中科院分区:
文献类型:
--
作者:
A. Weinstein
A classical theorem of Darboux may be stated as follows: if Sz is a closed 2-form of maximal rank on a 2n-dimensional manifold M and p is any point of M, then there exists a coordinate system x1,..., x,, y1,..., yn defined on a neighborhood U of p in M such that Sz= a!~, A dy,+...+ dx, A dy, on U. The purpose of this paper is to generalize Darboux’s theorem in several directions and to give some applications of the generalizations.The first direction of generalization is that the manifolds considered are Banach, rather than finite-dimensional, manifolds. Although our results in this context may have some use in theoretical mechanics, the main force of this generalization is that it requires us to use a method of proof other than induction on the dimension of M, which has been the standard proof technique for Darboux’s theorem. The new method of proof, first used in this context by Moser [12], enables us to obtain theorems concerning symplectic structures in the neighborhood of a closed submanifold, rather than just a point, of M. Another byproduct is an equivariant version of the Darboux theorem (Corollary 4.3). Our main result, Theorem 4.1, is most useful when applied to the so-called Zagrangian submanifolds of M. These, roughly speaking, are maximal submanifolds on which IR pulls back to zero. Essentially, Theorem 6.1 says that these submanifolds have no geometric invariants. This fact, in turn, has the surprising consequence (discussed at the end of Section 6) that a neighborhood of the identity in the symplectic automorphism group of a symplectic manifold may be smoothly parametrized by a neighborhood of zero in the Lie algebra of infinitesimal symplectic automorphisms. Section 7 is devoted to foliations of symplectic manifolds 329